Ac waveforms – Rainbow Electronics AT45DB021E User Manual
Page 50
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AT45DB021E [PRELIMINARY DATASHEET]
8789B–DFLASH–11/2012
22.
AC Waveforms
Four different timing waveforms are shown in
. Waveform 1 shows the SCK signal being
low when CS makes a high-to-low transition, and Waveform 2 shows the SCK signal being high when CS makes a
high-to-low transition. In both cases, output SO becomes valid while the SCK signal is still low (SCK low time is specified
as t
WL
). Timing Waveforms 1 and 2 conform to RapidS serial interface but for frequencies only up to 70MHz.
Waveforms 1 and 2 are compatible with SPI Mode 0 and SPI Mode 3, respectively.
Waveform 3 and 4 illustrate general timing diagrams for RapidS serial interface. These are similar to Waveform 1 and 2,
except that output SO is not restricted to become valid during the t
WL
period. These timing waveforms are valid over the
full frequency range (maximum frequency = 70MHz) of the RapidS serial case.
Figure 22-1. Waveform 1 = SPI Mode 0 Compatible
Figure 22-2. Waveform 2 = SPI Mode 3 Compatible
CS
SCK
SI
SO
t
CSS
Valid In
t
H
t
SU
t
WH
t
WL
t
CSH
t
CS
t
V
High-impedance
Valid Out
t
HO
t
DIS
High-impedance
CS
SCK
SO
t
CSS
Valid In
t
H
t
SU
t
WL
t
WH
t
CSH
t
CS
t
V
High Z
Valid Out
t
HO
t
DIS
High-impedance
SI